On Thu, Jul 30, 2015 at 03:42:26PM +0200, 'Klaus Aehlig' via ganeti-devel wrote:
When shrinking an instance do not shrink just in arbitrary
"unit" steps, but instead shrink until the failure statistics
changes. In this way, we only consider side branches (unilaterally
changing a single resource despite not the reason for the
majority of failures) only at places where we there is the possibility
to achieve something.
Signed-off-by: Klaus Aehlig <[email protected]>
---
src/Ganeti/HTools/Cluster.hs | 31 ++++++++++++++++++++++++-------
1 file changed, 24 insertions(+), 7 deletions(-)
diff --git a/src/Ganeti/HTools/Cluster.hs b/src/Ganeti/HTools/Cluster.hs
index a8313bf..f89a58a 100644
--- a/src/Ganeti/HTools/Cluster.hs
+++ b/src/Ganeti/HTools/Cluster.hs
@@ -868,6 +868,24 @@ underlyingCause :: FailMode -> FailMode
underlyingCause FailN1 = FailMem
underlyingCause x = x
+-- | Shrink a resource of an instance until the failure statistics for
+-- this resource changes. Note that it might no be possible to allocate
+-- an instance at this size; nevertheless there might be a need to change
+-- the resource to shrink on, e.g., if the current instance is too big on
+-- to resources.
+doShrink :: (Instance.Instance -> AllocSolution) -> Instance.Instance
+ -> FailMode -> Maybe Instance.Instance
+doShrink allocFn inst fm =
+ let physRes = underlyingCause fm
+ getCount = runListHead 0 snd . filter ((==) physRes . fst)
+ . collapseFailures . map underlyingCause . asFailures
+ initialStat = getCount $ allocFn inst
+ in case dropWhile ((==) initialStat . getCount . fst)
+ . map (allocFn &&& id)
+ $ iterateOk (`Instance.shrinkByType` physRes) inst
+ of x:_ -> Just $ snd x
+ _ -> Nothing
+
-- | Tiered allocation method.
--
-- This places instances on the cluster, and decreases the spec until
@@ -886,18 +904,17 @@ tieredAlloc opts nl il limit newinst allocnodes ixes
cstats =
Just (n - ixes_cnt))
sortedErrs = nub . map (underlyingCause . fst)
$ sortBy (flip $ comparing snd) errs
- suffShrink = sufficesShrinking
- (fromMaybe emptyAllocSolution
- . flip (tryAlloc opts nl' il') allocnodes)
- newinst
+ allocFn = fromMaybe emptyAllocSolution
+ . flip (tryAlloc opts nl' il') allocnodes
+ suffShrink = sufficesShrinking allocFn newinst
bigSteps = filter isJust . map suffShrink $ sortedErrs
progress (Ok (_, _, _, newil', _)) (Ok (_, _, _, newil, _)) =
length newil' > length newil
progress _ _ = False
in if stop then newsol else
- let newsol' = case map (Instance.shrinkByType newinst) sortedErrs of
- Ok newinst' : _ -> tieredAlloc opts nl' il' newlimit
- newinst' allocnodes ixes' cstats'
+ let newsol' = case map (doShrink allocFn newinst) sortedErrs of
+ Just newinst' : _ -> tieredAlloc opts nl' il' newlimit
+ newinst' allocnodes ixes' cstats'
_ -> newsol
in if progress newsol' newsol then newsol' else
case bigSteps of
--
2.5.0.rc2.392.g76e840b
LGTM
